The disclosure generally relates to low cost, low attenuation optical fibers for data transmission and, more particularly, relates to fiber designs with co-doped core regions.
Low attenuation (e.g., a fiber having an attenuation value of ≦0.17 dB/km) is an important characteristic of optical fibers configured to efficiently transmit data.
Fiber nonlinearity is also a factor limiting the performance of optical fibers used in high speed, long haul transmission applications. In general, fiber nonlinearity can be reduced by increasing the effective area of the fiber. This is because power density is inversely proportional to the effective area. While some fiber designs configured for single mode operation have focused on increasing the effective area, the effective area achieved by these designs has been limited by micro- and macro-bending losses. With recent advances in digital signal processing (DSP), linear impairment to transmission systems (e.g., chromatic dispersion and polarization mode dispersion (PMD)), is not a significant problem. Yet even with the advancements in DSP, the modal dispersion levels still should be minimized.
Multiple mechanisms can contribute to the attenuation and loss characteristics in optical fibers. These mechanisms can include Rayleigh scattering, small-angle scattering, metals and impurity-related absorption effects, and other UV and IR-related effects. Density and concentration fluctuations in the fibers can contribute to Rayleigh scattering. It is generally understood that the composition of the fiber regions (e.g., core and cladding), and their respective processing conditions, may influence these mechanisms.